We went out for a ride last summer and it ran fine. About 1 month later I was moving things around and it wouldnt start. I eventually got to run but it wouldnt stay running for long. I took a quick look at it and ordered a new airfilter and sparkplug. It ended up taking about 6 weeks to get the plug and filter and it was raining outside by that time so it got tarped off to be delt with in better weather. So last weekend I replaced the plug and airfilter and it's doing the same thing. It has a real hard time starting (after cranking for 10 to 15 seconds it will start and run for about 2 seconds and die). After doing this several times I can get it to stay running but only at mid throttle and even then it very slow to react to throttle changes. After it gets warmed up it will idle on its own for a maybe a minute but then die. So I have pulled the carb and "rebuilt it" ( basically pulled it apart and thouroughly cleaned it with carb cleaner, making sure nothing was cloged and no there was no sign of water or bad gas). FWIW the carb has never been adjusted or messed with in any way, untill now. So I am really curious about how the oil injection system works and also what is the function of the "starter plunger" solenoid on the carb. The spark seams fine. The only other thing I can think of is maybe there is a vacume leak in the plastic intake manifold.

I for the life of me cant figure this thing out. I have pulled the carb again and checked everything again. The oil injector pump seams to be working fine, the intake and reed setup is fine, the spark is fine, compression is fine. The only thing I cant figure out is what the purpose of the "starter plunger" solenoid is and if it is working properly. I have barowed a service manual for a 2005 Sportsman 90 but the carb is different and they dont have the solenoid, but they do have a manual choke, where mine dosnt.